In Patient #2, which factor related to lingual biofilm accumulation is NOT associated?

• A. Extended occlusal-apical height of implant prosthesis.
• B. Poor access angle for positioning toothbrush.
• C. Flat vertical contour of lingual surfaces of prosthesis.
• D. Lack of embrasure space between bicuspid prosthesis.

Answer: (D)

Lingual biofilm buildup on implant-supported prostheses is driven by how easily the tongue-facing surfaces can be cleaned and how much surface area and niche the prosthesis creates. An implant crown or prosthesis with extended occlusal-apical height tends to form deeper, harder-to-clean zones where plaque can accumulate. If the toothbrush cannot be positioned well due to a poor access angle on the lingual side, cleaning effectiveness decreases and biofilm is more likely to persist. A flat vertical contour on the lingual surfaces can also hinder effective brushing by reducing the natural cleaning action along that surface, again promoting plaque retention. By contrast, lack of embrasure space between bicuspid prostheses mainly concerns interdental cleaning between teeth; this factor does not directly create a lingual-area niche or impede cleaning on the tongue-facing surfaces, so it is not associated with lingual biofilm accumulation.